I. Field
The following description relates generally to wireless communications and more particularly to maximizing the Euclidean distance of coding, scrambling, and modulation for ACK/NAK.
II. Background
Wireless communication systems are widely deployed to provide various types of communication content such as voice, data, video, music, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., bandwidth and transmit power). Examples of such multiple-access systems include Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, 3GPP Long Term Evolution (LTE) systems, and Orthogonal Frequency Division Multiple Access (OFDMA) systems, and others.
Generally, a wireless multiple-access communication system can simultaneously support communication for multiple wireless terminals. Each terminal communicates with one or more base stations through transmissions on the forward and reverse links. The forward link (or downlink) refers to the communication link from the base stations to the terminals, and the reverse link (or uplink) refers to the communication link from the terminals to the base stations. This communication link can be established via a single-in-single-out, multiple-in-single-out or a multiple-in-multiple-out (MIMO) system.
As terminals or devices communicate with each other and send packets back and forth, the sending device should be made aware whether a packet has been received successfully or whether the packet should be retransmitted. As such, the receiving device can send an acknowledgement (ACK), which indicates that the packet was received successfully. If the packet was not received successfully, a negative acknowledgement (NAK) is transmitted. This negative acknowledgement indicates that the packet should be resent.
Hybrid Automatic Repeat-reQuest (HARQ) utilizes forward error correcting codes to correct a subset of errors and relies on the error detection to detect uncorrectable errors. Erroneously received packets are discarded and the receiving device requests retransmission of packets not successfully received. HARQ protection is available for data, however, retransmission of ACK/NAK on the uplink does not have HARQ protection.